Thursday, November 4, 2010

Why the early universe was free of charge: In 2006, Wilczek and Sean Robinson, both at the Massachusetts Institute of Technology, showed that the electromagnetic force also weakens at higher energies, but only in the presence of gravity, which is neglected in the standard model (Physical Review Letters, DOI: 10.1103/PhysRevLett.96.231601). Others punched holes in their calculations, however, and so the idea remained controversial. "We tried to do it without going through the heavy formal mathematics," Wilczek says.

Now David Toms of Newcastle University in the UK has redone the calculations more rigorously and come up with the same conclusions. In the presence of gravity, electric charge - a barometer of the strength of the electromagnetic force - tends to go to zero as energies rise (Nature, DOI: 10.1038/nature09506). "With no gravity, the electric charge gets bigger [with higher energies]," says Toms. "Gravity changes the picture."